Drill bit auxiliary



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P. IF. KERR DRILL BIT AUXILIARY w 1 .fl

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June 14, 1966 Filed Oct. l0, 1963 ELC -Huumvld June 14, 1966 P. F. KERR3,255,833

DRILL BIT AUXILIARY Filed Oct.. lO, 1965 3 Sheets-Sheet 2 June 14, 1966P. F. KERR 3,255,833

DRILL BIT AUXILIARY Filed Oct. lO, 1963 5 Sheets-Sheet 3 3,255,333 Drum.nir AUxrLrAnY Raul F'. Kerr, New York, N.Y., assignor to TexacoDevelopment Corporation, New York, N.Y., a corporation of Delaware Filed(Ict. 10, 1963, Ser.'No. 315,182 9 Claims. (Cl. 175-24) This inventionconcerns auxiliary apparatus for drilling in the earth. Morespecifically, it relates to auxiliary structure applicable to a rotarydrill, particularly of the type normally employed in deep well drillingoperations, usually for petroleum products.

A problem encountered quite often in drilling deep wells, particularlythose for oil or gas, is that of so-called blind holes or the loss ofreturn circulation of the drilling fluid. This invention is applicableto the situation where loss of circulation is due to a cavernencountered as the hole is drilled. Thus, it is an object of thisinvention to provide apparatus that may he employed with a rotarydrilling bit so as to apply a Wall-building paste around the drill bitwhenever a cavern, or open space is encountered during the drilling.

Another object of the invention is to provide auxiliary apparatusapplicable to rotary `drill structure having means associated with thebit for sensing a loss of formation under the bit. Such sensing means isthen applied to operate paste-containing tubes so as to extrude thepaste around the drill bit, in order to form a wall of paste which willblock the opening encountered.

Briefly, the invention is applicable to rotary well-drilling aparatusand relates 4to a drill bit auxiliary. The auxiliary comprises meanscontaining a paste for forming a wall at a cavern, encountered duringdrilling. It also comprises means associated with said bit for releasingsaid paste when said cavern is encountered.

The foregoing and other objects and benefits of this invention will bemore fully appreciated in connection with the detailed description whichfollows, and which is illustrated in the drawings wherein:

FIGURE 1 is a schematic cross-sectional view of the entire structureaccording to an embodiment of the invention, all shown located downholeadjacent to a subsurface cavern;

FIGURE 2 is an enlarged fragmentary perspective view showing the slidingdoors located near the lower ends of the paste tubes, which surround thedrill stem;

FIGURE 3 is another enlarged fragmentary perspective, showing the upperportion of the drill bit and illustrating the paste distributingmembers;

FIGURE 4 is an enlarged cross-section view taken along the lines 4 4 ofFIGURE l;

FIGURE 5 is another enlarged cross-section taken along the lines 5 5 ofFIGURE 1;

FIGURE 6 is another enlarged cross-section taken along the lines 6--6 ofFIGURE 1;

FIGURE 7 is an enlarged fragmentary vertical crosssection illustratingthe release structure for allowing the sliding doors to open as a cavernis encountered;

FIGURE 8 is a similar enlarged fragmentary vertical cross-section asthat of FIGURE 7, illustrating the position of the elements after acavern has been encountered; and

FIGURE 9 is an enlarged fragmentary vertical crosssection illustratingthe action of the paste distributing member as a cavern is encountered.

FIGURE 1 illustrates an embodiment of the invention and shows how itwould operate during the drilling operation, when an open space orcavern is encountered downhole. Thus, as a hole 11 is drilled in asubsurface formation 12 which is relatively solid, eg., that illustratedwith the reference numeral 12 applied thereto; the operice ation will besuch as to provide for drilling fluid 13 (usually called mud) to becirculated in a standard manner, i.e., down Within the hollow center ofa drill stem or pipe 14. The mud 13 flows also through a drill bit 15and then is circulated upward around the bit and Within the annulusformed Within the hole 11 surrounding the drill stem 14, so as' to clearaway the cuttings rnade by the drill bit and carry them to the surface.However, if lost circulation conditions are encountered, the auxiliaryapparatus according to this invention becomes effective as describedhereafter.

Thus, when a cavern is encountered, such as a cavern 18 illustrated, itwill not cause a loss of circulation of the drilling mud 13'which wouldordinarily take place by reason of the mud 13 flowing out into the'cavern 18 and therefore failing to return up through the hole 11 Withinthe annulus surrounding the drill stem 14. The action of the auxiliaryapparatus for accomplishing this will be better understoody as a moredetailed description thereof is given below.

Referring'to FIGURE l and the other figures of the drawings, it will beobserved that there are a plurality of paste tubes 19 that are arrangedperipherally surrounding the drill stem 14 just above but adjacent tothe drill bit 15. These paste tubes 19 will be long enough to contain anadequate amount of a heavy, viscous, slow-flowing paste 20 which will beused to build up a cylindrical wall, eg., a wall 17 which extendsvertically through any cavern, such as the cavern 18 illustrated. Thewall 17 is indicated by broken lines in FIGURE 1. The paste, of course,will be a material having adequate strength and adhesive qualities tobuild the wall in such manner that it can withstand the pressures towhich it must be subjected after drilling is resumed.

In order not to dilute the Wall building paste 20 as it is extruded fromthe paste tubes 19, there are provided two separate valves 21 and 22which act respectively to close the annulus and to cut olf the drillingmud circulation Within the drill stem 14 during the time that the pasteis being extruded from the paste tubes 19. The details of the structurefor these valves may vary but will be described in greater specicitybelow according to the illustrated embodiment of the invention.

It will be observed that the valves 21 and 22 are operated inconjunction with the operation of a plurality of sliding doors 25 thatact to close a corresponding plurality of ports or windows 26, onelocated near the bottom of each of the paste tubes 19. These slidingdoors 25 are actuated from a supporting ring 27 that surrounds the drillstem just above the bit 15. The vertical position of ring 27 isdetermined by a plurality of drop rods 30 which have enlarged stopshoulder portions 31 located above the top surface of the bit 15. Inaddition there is an inner ring 32 that is attached to ring 27 by radialrods 34. Also ring 32 has attached thereto a plurality of paste catchingmembers 33. These paste catching members are hinged at the ring 32 sothat they may be retracted (as is illustrated in FIGURE 9 by the dashedline showing) when the drop rods 30 are moved vertically upward to theretracted positions thereof. The latter takes place when the bit is incontact with the subsurface formation.

The operation of the inner valve 22 is controlled by a different set ofdrop rods 36 that are located radially inward relative to the drop rods30, but similarly extend vertically through the body of the bit 15. Droprods 36 have enlarged stop shoulders 37 which prevent the drop rods frommoving vertically downward beyond a predetermined distance and alsosupport the valve structure of valve 22 when it is i-n its closedposition.

The upper valve 21 is for cutting off drilling mud circulation in theannulus. It is located above the top of the paste tubes 19 andsurrounding the exterior of the drill stem 14. This valve 21 isconstructed of a plurality of overlapping hinged flaps or petals 38.Actuation of these petal elements of valve 21 is carried out by aplurality of vertically extending rods 40 that are attached to certainof the petals which make up the valve 21. These petals are attached ineach case by a clevis 41 and hinge'pin as shown. The clevis is attachedto one of the petals of the fan type structure which lies underneathadjacent petals thereof. This structure is shown in greater detail inFIGURE where it will be observed that there are alternate petals 38 withthe two clevises 41 being attached to oppositely located ones of thepetals 38. By having this structure, when the rods 40 are verticallyraised they will move the petals 38 (having the clevises 41 attachedthereto) so as to cause all of the petals to pivot about their hingeswhich are fastened to the outside of the drill stem '14, as illustrated.Thus, when rods 40 are moved vertically upward they cause all of thepetals 38 to fold against the drill stem 14 and thus leave the annulussurrounding the drill stern open.

Movement of the rods 40 is carried out by the supporting structurethereof which includes a ring 45 that surrounds the paste tubes 19 andto which ring the rods 40 are attached. Also attached to the ring 45,but extending vertically downward therefrom there are a plurality ofrods 46. Each of the rods 46 have attached to the lower end thereof across member 47 (FIGURE 2) that may slide vertically in grooves 50(FIGURE 6). The grooves 50 are located on the inner edges of thatportion of the paste tubes 19 which contain the windows 26. Crossmembers 47 will encounter a stop surface (not shown) in the grooves 50at the upper edge of the windows 26 to limit the downward movement ofthe whole supporting structure for the rods 40 so that the fan valve 21will be stopped in its extended or closed position. However, they arefree to move or slide vertically upward from this position so as tocarry the ring 45 upward and consequently move the rods 40 up in orderto open the valve 21.

It will be observed that movement of the cross members 47 upward in thegrooves 5t) is caused by the vertically sliding doors when they havecontacted the cross members after having closed the windows 26.Furthermore, actuation of the doors 25 takes place by reason of movementof attached rods 51 which extend downward from the bottom of the doors25 and are connected to the ring 27. Ring 27 rests on and is moved bythe drop rods and stop shoulders 31.

In order to provide for holding the windows 26 closed and the valves 21and 22 open during normal drilling Operations, there is a latchingstructure in connection with the drop rods 30, such as that illustratedin FIG- URES 7 and 8. This latching structure includes a round headedbolt 55 that is carried in a recess 56 in the bit 15. There is also apassageway 57 that connects the recess 56 with an inner enlarged hole orspace 58 that is large enough to accommodate a locking pair of nuts 59that are placed on the bolt 55 to act as a stop for the extendedposition of the bolt. The inner end of bolt 55 extends into a notch 62located in the corresponding drop rod 30 when the bolt 55 is held in itsretracted position by the presence of a solid formation wall, eg., theformation 12 as illustrated in FIGURES 7 and 8. There is a coil spring63 which surrounds the body of bolt 55 and rests against the at side ofthe head of the bolt at one end and against the at surface of the recessat the other end of the spring.

As illustrated in FIGURES 7 and 8 the latching arrangement is such thatthe drop rods 30 will be held upward in their retracted position by thelatching action of bolt 55 cooperating with the notch 62 so long as thebolt is in its retracted, or radially inward, position. The latch willremain engaged so long as the walls of the hole being drilled aresufficiently solid. However', whenever a cavern or opening in thesubsurface formations is encountered then the bolt 55 will move radiallyoutward under pressure of the spring 63, to the position illustrated inFIGURE 8. This then releases the drop rods 30 so that the doors 25 willslide down and rst close the fan valve 21 and then open the windows 26to allow the paste 20 to be extruded from the tubes 19. The drop rods 36will already have been released by absence of any formation below thebit, so that the downward circulating mud stream will have already beencut off by the consequent closing of the valve 22.

OPERATION The operation of the apparatus according to this inventionwill be described in relation to the conditions' existing during adrilling procedure as the drill reaches a cavern or opening in thesubsurface formation. Thus, it is to be noted that as soon as such acavern (e.g., cavern 18 illustrated in FIGURE l) is reached the droprods 30 will move vertically downward relative to the bit 15 as soon asthe latching mechanism has released the drop rods. However, before thisaction of downward movement of drop rods 30 takes place, the drop rods36 will have been released by the lack of formation under the bit 15 andthe valve 22 will have been closed to cut ott` the flow of drilling mud13.

When the drop rods 30 are released by the latching mechanism, as the bit15 enters the cavern, their downward movement causes opening of thedoors 25 'to allow outward flow or extrusion of the paste 20 through theports or windows 26, to take place. Also, opening of the doors 25 rstallows downward movement of the cross members 47 and consequentlymovement of the rods 40 which control the upper fan valve 21. This fanvalve 21 then blocks circulation of drilling mud through the annuluswithin hole 11 surrounding the drill stem 14. Then, although thepressure existing down hole acts upon the paste 20 within the tubes 19,gravity or total pressure differentials will cause the paste to beexuded outward through the windows or ports 26 and down around the lowerend of the paste tubes 19 until it contacts the outer edges of the pastecatching members 33 which are now extended by reason of the downwardmovement of the ring 27 and connected inner ring 32 to which the mudcatching members are attached. It will be appreciated that centrifugalforce involved in the rotation of the whole `unit (with drill stem 14and bit 15) will act to assist the flow of paste 20 out of the tubes 19so as to produce a slow extrusion rather than a mere exusion. The paste20 will then build up to form the cylindrical wall 17 which will extenddownward as long as there is sufficient paste, and will thus provide aclosure or seal for the cavern 18 so that the drill bit may continuewithout loss of circulation in the formation beneath.

It will be appreciated by anyone skilled in the art that in order forthe foregoing build up of the paste 20 to form a cylindrical wall 17, asindicated, the proper consistency of the paste will be necessary. Suchconsistency will include suicient body and/or adhesive quality (relativeto the bore hole wall) to ensure that paste will be added to the lowerend of the wall as it is formed.

Thus, the hole 11 may continue and as the hard formation is once morecontacted below the cavern 18, the stop rods 30 and 36 will be retractedvertically upward and will return the valves 21 and 22 respectively totheir open positions while also retracting the paste catching members 33and closing the windows 26 at the same time. In this manner all of theelements will be restored to the normal position for drilling, and thecavern will have been effectively sealed off.

While a particular embodiment according to this invention has beendescribed above in considerable detail in accordance with the applicablestatutes, this is not to be taken as in any way limiting the inventionbut merely as being descriptive thereof.

I claim:

ll. In rotary well drilling apparatus including a bit and a stemtherefor, a drill bit auxiliary adapted for applying paste to form acavity sealing wall comprising tube means surrounding the stem of saidbit for containing said paste an-d having a closeable opening forextruding said paste, and means associated with said bit for holdingsaid opening closed so long as formation is being encountered by thebit.

2. In rotary well drilling apparatus including a bit and a stemtherefor, a drill bit auxiliary adapted for applying paste to form acavity sealing wall comprising a plurality of paste tubes surroundingthe stem of said bit for containing said wall building paste therein,each of said tubes having an extrusion port near the base thereof, aplurality of vertically slideable doors for closing said ports, andmeans associated with said bit for holding said doors closed in thepresence of a formation under the bit while drilling.

3. In rotary well drilling apparatus including a bit and a stem attachedthereto in supporting relation thereof, said stem having an axialpassage there-through for allowing drilling fluid to be circulatedtherein, a drill bit auxiliary adapted `for applying paste to form acavity sealing wall comprising a plurality of paste tubes surroundingthe stem of said bit for containing said wall building paste therein,each of said tubes having an extrusion port near the base thereof, aplurality of vertically slideable doors for closing said ports,formation sensing means associated with said bit, irst and second valve4means attached to said stem for cutting off the circulation of drillingiluid in said stem and in the annulus around said stem, and meansactuated by said sensing means `for opening said ports and closing saidvalve means upon the loss of formation at said bit.

4. A drill bit auxiliary according to claim 3 wherein said formationsensing means comprises a plurality of drop rods located in said bit.

5. A drill `bit auxiliary according to claim 4 wherein 5 said meansactuated by said sensing means comprises a supporting ring for saidslideable doors and enlarged stop shoulders on said drop rods forsupportably contacting said ring.

6. A drill bit auxiliary according to claim 5 further including a secondring mounted above said supporting ring and having rods connectedthereto for actuating said second valve means, and means for moving saidsecond ring with `said rst ring when said doors are closed.

7. A drill bit auxiliary according to claim 6 further including meansfor connecting some of sai-d drop rods to said rst valve means foractuating same.

8. A drill bit auxiliary according to claim 7 further including latchingmeans for holding at least `some of said drop rods in a retractedposition so long as the walls of the formation at said bit location aresolid.

9. A drill bit auxiliary according to claim 8 further includingretractable paste catching members for supporting said paste as it isextruded from said tubes.

References Cited by the Examiner UNITED STATES' PATENTS 1,313,013 9/1919Polysu 26a-32 1,574,040 2/1926 Lasher 166-23 x 30 1,916,686 7/1933sandstone 166-24 FOREIGN PATENTS 380,451 9/1932 Great Britain.

35 CHARLES E. OCONNELL, Primary Examiner.

R. E. FAVREAU, Assistant Examiner.

1. IN ROTARY WELL DRILLING APPARATUS INCLUDING A BIT AND A STEMTHEREFOR, A DRILL BIT AUXILIARY ADAPTED FOR APPLYING PASTE TO FORM ACAVITY SEALING WALL COMPRISING TUBE MEANS SURROUNDING THE STEM OF SAIDBIT FOR CONTAINING SAID PASTE AND HAVING A CLOSEABLE OPENING FOREXTRUDING SAID PASTE, AND MEANS ASSOCIATED WITH SAID BIT FOR HOLDINGSAID OPENING CLOSED SO LONG AS FORMATION IS BEING ENCOUNTERED BY THEBIT.